Man walking past invisible bodies. Photo: Getty Images
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Scientists suggest invisibility as a cure for anxiety

Neuroscientists have made the surprise discovery that the sensation of invisibly reduces responses to anxiety.

Have you ever felt fear and anxiety from standing in front of a large audience and giving a speech? Or how about having to get up in class and talk to other students? While it's normal in situations like these to wish for the ground to swallow you up, some scientists have suggested a slightly different remedy for anxiety - invisibility.

Invisibility has long featured in myths and fiction, but several advances in material sciences have demonstrated that the cloaking of large (living) objects - just like how the invisibility cloak works in Harry Potter - is becoming a realistic prospect. In the field of material sciences, the general concept of invisibility cloaking is actually fairly simple.

Theoretically, all that's needed is a material that guides visible light (or another wave, like EM waves or heat fluxaround an object, and anything within the gap it leaves will be rendered "invisible" to someone standing at the light source:

Light moves around the object (or person) as though it isn't there. Image: Trevor Johnston/trevorjohnston.com

In practice, this is hard to achieve, as most naturally occurring materials reflect light, cast shadows and produce a reflection. However, hi-tech and exotic materials called "metamaterials" have made light bending possible. (Although latest research suggest that ordinary lenses can do just the trick!)

H G Wells, a man ahead of his time, wrote the The Invisible Man in 1897. The novel is about a protagonist who invents a method to change the human body’s refractory index to that of the air, rendering it invisible. (The twist comes when he performs the method on himself and can’t reverse it - but that’s beside the point.) The refractive index is the ratio between how light passes through a vacuum, and how it passes through any other medium; it’s the reason a spoon will look bent when placed in a glass of water. If water has a negative refractive index, the spoon would look as though as was bending back on itself instead.

In a recent paper in Scientific Reports, graduate students Arvid Guterstam and Zakaryah Abdulkarim and their advisor Henrik Ehrsson, a neuroscience professor at the Karolinska Institutet in Stockholm, said they believe invisibility cloaking of the human body is a thing of the future, and believe it’s high time we delve into what it feels like to be invisible.

To do this, Guterstam, Abdulkarim, and Ehrsson used virtual reality. In one of their experiments, 23 people were provided with a set of head-mounted displays (HMD), and were asked to look at their feet. The experimenter - Abdulkarim - stroked their arms, legs, and torso with a paintbrush with one hand, and at the same time, made identical motions with a second paintbrush with the other hand, on an invisible body or a mannequin. A pair of downward-facing cameras that were either mounted on a tripod or on the head of a mannequin sent a real-time video feed to the participants HMDs, giving them the sensation of being invisible, or making a body swap with a mannequin:

Study co-author Zakaryah Abdulkarim (middle) creates the invisible body illusion on a participant (left) wearing a set of head-mounted displays connected to a pair of cameras. Photo: Staffan Larsson

Here's the surprise: after finishing with the paintbrush, each participant slowly lifted their gaze through their HMDs to find that they were being watched by a scornful-looking audience (consisting of 11 scientists instructed to stare at the participant). Quite creepy, and perhaps enough to through most people off - however, on a 100-point scale, participants reported their stress level as about 25 per cent lower, on average, when in a state of invisibility, and about a third less than in the mannequin version. The state of invisibility also lowered heart rates by a few beats per minute, suggesting that stress is intertwined with physiology.

The researchers write: “Our results demonstrate that healthy individuals can experience the illusion of owning an invisible full body." They suggest their results could spur on better a design for virtual-reality based therapies for social anxiety, and may also help give neuroscientists gain new insight into phantom limb illusions.

Tosin Thompson writes about science and was the New Statesman's 2015 Wellcome Trust Scholar. 

Davide Restivo at Wikimedia Commons
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Scientists have finally said it: alcohol causes cancer

Enough of "linked" and "attributable": a new paper concludes that alcohol directly causes seven types of cancer.

I don't blame you if you switch off completely at the words "causes cancer". If you pay attention to certain publications, everything from sunbeds, to fish, to not getting enough sun, can all cause cancer. But this time, it's worth listening.

The journal Addiction has published a paper that makes a simple, yet startling, claim: 

"Evidence can support the judgement that alcohol causes cancer of the oropharynx [part of the throat], larynx, oesophagus, liver, colon, rectum and [female] breast"

So what's especially significant about this? 

First, scientists, unlike journalists, are very wary of the word "causes". It's hard to ever prove that one action directly led to another, rather than that both happened to occur within the same scenario. And yet Jennie Connor, author of the paper and professor in the Preventive and Social Medicine department at the University of Otago, New Zealand, has taken the leap.

Second, alcohol not only causes cancer of one kind – the evidence supports the claim that it causes cancer at seven different sites in our bodies. There was weaker evidence that it may also cause skin, prostate and pancreatic cancer, while the link between mouth cancers and alcohol consumption was the strongest. 

What did we know about alcohol and cancer before?

Many, many studies have "linked" cancer to alcohol, or argued that some cases may be "attributable" to alcohol consumption. 

This paper loooks back over a decade's worth of research into alcohol and cancer, and Connor concludes that all this evidence, taken together, proves that alcohol "increases the incidence of [cancer] in the population".

However, as Connor notes in her paper, "alcohol’s causal role is perceived to be more complex than tobacco's", partly because we still don't know exactly how alcohol causes cancer at these sites. Yet she argues that the evidence alone is enough to prove the cause, even if we don't know exactly how the "biologial mechanisms" work. 

Does this mean that drinking = cancer, then?

No. A causal link doesn't mean one thing always leads to the other. Also, cancer in these seven sites was shown to have what's called a "dose-response" relationship, which means the more you drink, the more you increase your chances of cancer.

On the bright side, scientists have also found that if you stop drinking altogether, you can reduce your chances back down again.

Are moderate drinkers off the hook?

Nope. Rather devastatingly, Connor notes that moderate drinkers bear a "considerable" portion of the cancer risk, and that targeting only heavy drinkers with alcohol risk reduction campaigns would have "limited" impact. 

What does this mean for public health? 

This is the tricky bit. In the paper, Connor points out that, given what we know about lung cancer and tobacco, the general advice is simply not to smoke. Now, a strong link proven over years of research may suggest the same about drinking, an activity society views as a bit risky but generally harmless.

Yet in 2012, it's estimated that alcohol-attributable cancers killed half a million people, which made up 5.8 per cent of cancer deaths worldwide. As we better understand the links between the two, it's possible that this proportion may turn out to be a lot higher. 

As she was doing the research, Connor commented:

"We've grown up with thinking cancer is very mysterious, we don't know what causes it and it's frightening, so to think that something as ordinary as drinking is associated with cancer I think is quite difficult."

What do we do now?

Drink less. The one semi-silver lining in the study is that the quantity of alcohol you consume has a real bearing on your risk of developing these cancers. 

On a wider scale, it looks like we need to recalibrate society's perspective on drinking. Drug campaigners have long pointed out that alcohol, while legal, is one of the most toxic and harmful drugs available  an argument that this study will bolster.

In January, England's chief medical officer Sally Davies introduced some of the strictest guidelines on alcohol consumption in the world, and later shocked a parliamentary hearing by saying that drinking could cause breast cancer.

"I would like people to take their choice knowing the issues," she told the hearing, "And do as I do when I reach for my glass of wine and think... do I want to raise my risk of breast cancer?"

Now, it's beginning to look like she was ahead of the curve. 

Barbara Speed is a technology and digital culture writer at the New Statesman and a staff writer at CityMetric.